1. Field of the Invention:
This invention relates to a resectoscope provided with a fixed position adjusting means in an electrode fixing mechanism for fixing an electrode.
2. Related Art Statement:
Recently, there has come to be extensively used an endoscope whereby an elongate insertable part can be inserted into a body cavity to observe the interior of the body cavity without incising it or to cure it by using a treatment tool.
For the above mentioned endoscope, there is a resectoscope which can be inserted through a urethra to resect a swollen prostate or the like.
In such resectoscope, an optical sighting tube for observation and an electrode as a resecting means are inserted through a hollow sheath and this electrode is fixed at the rear end to an electrode fixing mechanism provided in a slider of a handle so as to project out of and retreat into the front end of the sheath.
In such electrode fixing mechanism shown in U.S. Pat. No. 4,149,538, the electrode is fixed by the engagement of an offset provided at the rear end of the electrode with an opening provided in a plunger reciprocatable in the direction intersecting with the axial direction of the electrode.
Also, in the one shown in the Gazette of Japanese Utility Model Publication No. 33,929/1986, an electrode fixing member is provided within a movable member fixing the electrode at the rear end and is provided with a slit to form a flexing piece, an electrode holding space is formed within this slit and a pressing part pressing the flexing piece on the side to narrow the width of the above mentioned slit or the electrode holding space is provided on the side of the above mentioned movable member.
In these related art examples, an operation of pushing a button or rotating a grip was necessary to fix the electrode.
On the other hand, in the Gazette of Japanese Utility Model Laid Open No. 144,406/1985, there is shown an electrode fixing mechanism whereby the electrode is automatically fixed by the operation of inserting the electrode into an electrode inserting hole.
This related art example shall be explained with reference to FIGS. 6 and 7.
That is to say, an inserting hole 3 with which an electrode 2 is to be engaged on the rear end side is provided on the front end surface side of a slider 1. On the other hand, there is formed an incised recess 5 which communicates with the depths of the hole 3 from the side intersecting at right angles with this inserting hole 3 and in which a guide frame 4 made of a metal to lock the above mentioned electrode 2 at the rear end is to be contained. The guide frame 4 contained in this recess 5 is provided with a hole 6 in the position facing the above mentioned inserting hole 3 so that the electrode 2 may pass at the rear end through this hole 6 and may collide at the rear end with the recess opposed to this hole 6. An electrode fixing member 8 provided with an electrode fixing incision 7 is engaged on the tip side with this guide frame 4. A sloped part 9 projecting on the inserting depth side of the electrode 2 is formed in this incision 7. On the other hand, the electrode 2 is provided near the rear end with an incision 11 so as to be fixed as prevented by this sloped part from being removed. Outside the above mentioned electrode fixing member 8, a guide frame fixing member 12 pressing and fixing the above mentioned guide frame 4 in a predetermined position is pressed into the recess of the slider 1. This guide frame fixing member 12 is cylindrical, has the electrode fixing member 8 slidably inside it and is covered on the outer periphery with a cap 14 through a coil spring 13. The electrode fixing member 8 is energized by the above mentioned coil spring 13 in the direction of projecting out of the recess of the slider 1 together with the cap 14. The sloped part 9 is set by this energiging force to project in the center direction of the hole 6 from the peripheral edge position of the hole 6 of the guide frame 4 communicating with the inserting hole 3. Therefore, in case the electrode 2 inserted through this hole 6 is inserted at the rear end to the depth side by pressing this sloped part 9 (energized by the coil spring 13) and in case the electrode 2 is inserted in the incision 11 near the rear end over the sloped part 9, the sloped part 9 pressed and moved by the energizing force of the coil spring 13 will be returned and will remain engaged with the incision 11 and the electrode 2 will be automatically fixed. By the way, on the outer periphery near the end of the guide frame fixing member 12, a recess is formed in the part opposed to the inner periphery of the cap 14 and is fitted with a water-tight O-ring 15. In FIG. 6, the reference numeral 16 represents a scope guide tube and 17 represents an electrode cord connector.
In the structure of the above mentioned related art example, as no mechanism of adjusting the position of the sloped part 9 of the electrode fixing member 8 is provided, there has been a defect that, due to the fluctuation of the dimensions of the parts forming the electrode fixing mechanism and the faulty adjustment in assembling, in case the electrode 2 is inserted, it will not collide at the rear end with the sloped part 9 and will not be sufficiently fixed.